Sludge extractor

ABSTRACT

A sludge extractor with a receiving tank, on which a suction connection for a suction element, which draws in a sludge-containing liquid, and a discharge connection for discharge element, which discharges the sludge-containing liquid, are mounted, and with a motor for driving a suction device in such a way that a negative pressure is created in the receiving tank, which negative pressure keeps a vacuum valve on the discharge element closed, is characterized in that the negative pressure acting on the vacuum valve is lower than the pressure which acts on the vacuum valve as a result of the sludge-containing liquid when a predetermined fill level is reached by the sludge-containing liquid in the receiving tank.

PRIORITY CLAIM

This is a U.S. national stage of application No. PCT/DE02/03643, filedon Sep. 25, 2002. Priority is claimed on that application and on thefollowing application(s): Country: Germany, Application No.: 101 47018.5, Filed: Sep. 25, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to a sludge extractor with a receivingtank, on which are mounted a suction connection for a suction element,which draws in a sludge-containing liquid, and a discharge connectionfor a discharge element, which discharges the sludge-containing liquid,the extractor also being equipped with a motor to drive a suction devicein such a way that a negative pressure, which keeps a vacuum valve onthe discharge element closed, is created in the receiving tank.

2. Description of the Prior Art

A sludge extractor of this type is known from DE 199 42 187 A1. Thesuction process is begun by turning on the motor. The receiving tankfills up slowly with sludge-containing liquid until the liquid reachesthe level of the vacuum valve. The vacuum valve is closed because of theprevailing negative pressure. When a the liquid reaches a certain limitin the receiving tank, a ball valve closes, as a result of which themotor begins to run audibly faster. This is a sign to the user that it'stime to turn off the motor. Turning off the motor has the effect ofeliminating the negative pressure in the receiving tank. The internalpressure now being produced by the sludge-containing liquid has theeffect of opening the vacuum valve, and the sludge-containing liquid cannow escape through the discharge element until the receiving tank isempty again. Then the user can turn the motor on again to repeat theprocess as often as necessary.

A sludge extractor of this type therefore suffers from the disadvantagethat the receiving tank, which fills up relatively quickly, can only beemptied discontinuously, by turning off the motor.

A procedure of this type leads to many interruptions in the suctionprocess itself, and many users find this annoying.

SUMMARY OF THE INVENTION

The task of the present invention is therefore to create a sludgeextractor which is able to perform wet-vacuuming continuously.

The task is accomplished according to the invention in that, when thesludge-containing liquid reaches a predetermined level in the receivingtank, the negative pressure acting on the vacuum valve is weaker thanthe pressure acting on the vacuum valve as a result of thesludge-containing liquid.

The sludge extractor according to the invention offers the advantagethat suction can be carried out continuously without the need to turnthe unit off repeatedly during the course of the vacuuming process.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention is described in greater detailbelow on the basis of the drawings:

FIG. 1 shows a schematic diagram of a sludge extractor according to thepresent invention; and

FIG. 2 shows a schematic diagram, in cross section, of the sludgeextractor according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An inventive sludge extractor 1 (FIG. 1) comprises a housing 1.1, onwhich a suction connection 1.2 for a suction element 3 and a dischargeconnection 1.3 for a discharge element 5 are formed. The housing 1.1 isalso designed with a cover 1.4 in its upper area, i.e., the area at theopposite end from the bottom. The cover 1.4 is fastened detachably tothe lower housing 1.1. At the bottom, the housing 1.1 is provided with abase element 1.5. The central area of the interior of the housing 1.1 isdesigned as a receiving tank 1.6 for the sludge-containing liquid,usually a mixture of sludge and water or materials of similarconsistency. The suction connection 1.2 is located in the upper part ofthe receiving tank 1.6, and the discharge connection 1.3 is located inthe lower part of the receiving tank 1.6.

Above the receiving tank 1.6, that is, above the area of the housing 1.1which can be filled with sludge and water, a motor 1.7, preferably anelectric motor, is mounted, which drives a generally known suctiondevice 1.8 such as an air-drawing vane element (FIG. 2). While thedevice is being driven, air is drawn from the receiving tank 1.6 andconveyed to the outside via air outlet openings 1.9 in the upper area ofthe housing. As a result, a negative pressure is created in thereceiving tank 1.6 and in the suction element 3.

The motor 1.7 has a drive shaft 1.10 for the suction device 1.8. Thefree end 1.11 of this shaft extends to a point near the bottom of theinterior of the receiving tank 1.6. The suction device 1.8 or pump ismounted at the free end 1.11 of the drive shaft 1.10. The suction device1.8 is seated in a flow channel 1.12, which establishes a directconnection to the discharge connection 1.3. In the immediate vicinity(in the present embodiment, below) of the suction device 1.8, a firstliquid inlet 1.13 a is provided, through which the indrawnsludge-containing liquid is admitted. Between the suction device 1.8 andthe discharge connection 1.3, a second liquid inlet 1.13 b is providedin the suction channel 1.12, via which the vacuum valve 5.2 in thedischarge connection 1.3 can be decoupled.

The drive shaft 1.10 is supported in a sealed, protective housing 1.14.In the area of the maximum level MAX for water or sludge, a safety valve1.15 is provided, which closes the air outlets 1.9 when the maximumwater level is reached. The safety valve 1.15 is a float valve. In thepresent embodiment, the drive shaft 1.10 and its protective housing 1.14are mounted in the center of the receiving tank 1.6. In otherembodiments, the drive shaft 1.10 could also be mounted off-center inthe receiving tank 1.6.

The safety valve 1.15 is concentric with respect to the drive shaft1.10. Also concentric with respect to the drive shaft 1.10 and itsprotective housing 1.14 is a prefilter 1.16. The prefilter 1.16 isinstalled near the inside wall of the receiving tank 1.6 and serves tokeep coarse material such as leaves, small twigs, gravel, etc., awayfrom the suction device 1.8. There is a certain gap between the insidecircumference of the prefilter 1.16 and the protective housing 1.14 ofthe drive shaft 1.10.

The upper suction connection 1.2 is located at the level of the maximumwater or fill level. The flow route is limited on the inside by a wall1.17 of the centrally mounted safety valve 1.15, so that the incomingsludge-containing liquid is diverted downward into the prefilter 1.16adjacent to the safety valve and then emerges from this filter on allsides or at least radially toward the inside.

The safety valve 1.15 is limited laterally on the outside by the wall1.17 and on the inside by the protective housing 1.14. In the enclosedspace of the safety valve 1.15, a ring-shaped float 1.18 is provided,which, at low water or fill levels, closes off an opening 1.19 at thebottom (the dotted line outline of float 1.18 in the figure shows theposition at low water levels). As the water or fill level rises, thesludge-containing liquid rises through the opening 1.19 and lifts thering-shaped float 1.18 until the ring-shaped float 1.18 closes off theair outlet 1.9 the solid line outline of float 1.18 in the figure showsthe position proximate the MAX fill level).

The suction element 3 (FIG. 1) is fastened detachably to the suctionconnection 1.2 in the generally known manner and is equipped optionallywith a radio-control switch 3.2 in a gripping area 3.1. In addition, asuction line 3.3 is formed on the free end of the suction element 3,onto which a suction nozzle (not shown) can be placed. The suctionelement 3 can be a hose or a pipe.

A discharge element 5 is mounted detachably in the generally knownmanner on the discharge connection 1.3 and has a vacuum valve 5.2 at itsfree end 5.1. The discharge element 5 can also be a hose or a pipe. Thevacuum valve 5.2 can also be installed in the discharge connection 1.3or in any other desired position between the discharge connection 1.3and the free end 5.1.

The device functions as follows.

The suction line 3.3 and optionally the suction nozzle of the suctionelement 3 hangs down into the water, near the bottom of the pond. Thesuction process is begun by turning on the motor 1.7, which can be done,for example, by radio control switch 3.2. Via the suction line 3.3,sludge is sucked from the bottom of the pond. The sludge thus passesthrough the suction element 3 and into the receiving tank 1.6. Thereceiving tank 1.6 fills up slowly with sludge as far as the level ofthe vacuum valve 5.2. The vacuum valve 5.2 is kept closed by theprevailing negative pressure. When the liquid reaches a predeterminedlevel in the receiving tank 1.6, i.e., the level at which the pressurebeing exerted via the liquid inlet 1.13 on the vacuum valve 5.2 isgreater than the negative pressure keeping the vacuum valve 5.2 closed,the vacuum valve 5.2 opens automatically, so that the sludge-containingliquid can flow out continuously through the discharge opening 1.3.

A discharge element 5 such as a hose can be connected to the dischargeopening 1.3 by means of a standard commercial quick-connect device; thefree end 5.1 of this hose can be placed anywhere desired such as at aplace where the sludge is to be dumped.

In addition to radio-control operation switch 3.2, a switch arrangementis also provided directly on the sludge extractor 1 in order to turn thesludge extractor on and off.

In other exemplary embodiments, two separate motors can be provided, sothat a suction device near the bottom and another suction devicerelatively far away from the bottom can each be operated by its ownmotor.

The cover 1.4, the motor 1.7, the drive shaft 1.10, and the suctiondevice 1.8 can be assembled as a unit and mounted so that they can beremoved all at once. The prefilter 1.16 can also be removed as a unit.The unit and the prefilter can thus be easily detached from thereceiving tank 1.6 for the purpose of cleaning.

1. A sludge extractor, comprising: a receiving tank having a suctionconnection connected to a suction element which draws insludge-containing liquid and a discharge connection connected to adischarge element which discharges the sludge-containing liquid from thereceiving tank; a motor connected to a suction device, wherein saidmotor is operable for driving said suction device such that a negativepressure is created in said receiving tank; a vacuum valve arranged inthe discharge element, wherein the negative pressure acts on said vacuumvalve and holds said vacuum valve closed until the sludge-containingliquid reaches a predetermined level at which level the pressure of thesludge-containing liquid acting on said vacuum valve surpasses thenegative pressure acting on said vacuum valve and said valve opens, saidvacuum valve being configured to open while said motor continues tooperate said suction device to draw in the sludge containing liquid; anda safety valve installed in said receiving tank proximate a maximum filllevel of said receiving tank.
 2. The sludge extractor of claim 1,wherein said motor includes a drive shaft having a free end whichextends to a position proximate a bottom of the interior of saidreceiving tank, said suction device being mounted on said free end. 3.The sludge extractor of claim 2, wherein said drive shaft is mounted ina center of said receiving tank.
 4. The sludge extractor of claim 3,further comprising a prefilter mounted in said receiving tank receivingthe sludge-containing liquid drawn in through said suction connection,wherein said prefilter is mounted concentrically with respect to saiddrive shaft.
 5. The sludge extractor of claim 3, wherein said safetyvalve is ring-shaped and is mounted concentrically with respect to saiddrive shaft.
 6. The sludge extractor of claim 4, wherein said safetyvalve is ring-shaped and is mounted concentrically with respect to saiddrive shaft.
 7. The sludge extractor of claim 1, further comprising aflow channel arranged in said receiving tank and extending between saidsuction device and said discharge connection, said suction device beinglocated within said flow channel, said flow channel having a firstliquid inlet arranged at an intake side of said suction device for theliquid to be drawn into said flow channel and a second liquid inlet forthe liquid arranged on a discharge side of said suction device.
 8. Thesludge extractor of claim 1, further comprising a prefilter mounted insaid receiving tank receiving the sludge-containing liquid drawn inthrough said suction connection.
 9. The sludge extractor of claim 1,wherein said safety valve is a float valve.